[comp.sys.amiga.hardware] ROM pinout confusion

danbabcock@eklektik.UUCP (/dev/ph1) (05/25/90)

grr@cbmvax (George Robbins) wrote:

>It has - the extra pair of sockets is there only to support ROMS/EPROM with
>mutually incompatible pinouts.  They are very likely to dissapear on
>production systems.

I hope it's the nonstandard pinout that disappears and not the other!
I don't understand why the 500/2000 uses a nonstandard pinout; what's the
motivation? Secondly, since you have to make two sets of ROMs anyway
(a 16-bit version and a 32-bit version), there's no reason to choose
an incompatible pinout for the 3000's ROMs (i.e. backward compatability
is not an issue). Could you please clarify? (thanks!)

-- Dan Babcock
Internet: danbabcock@eklektik.pgh.pa.us
People/Link: DANBABCOCK
Phone: (412)-373-1753

grr@cbmvax.commodore.com (George Robbins) (05/27/90)

In article <3276@eklektik.UUCP> danbabcock@eklektik.UUCP (/dev/ph1) writes:
> grr@cbmvax (George Robbins) wrote:
> 
> >It has - the extra pair of sockets is there only to support ROMS/EPROM with
> >mutually incompatible pinouts.  They are very likely to dissapear on
> >production systems.
> 
> I hope it's the nonstandard pinout that disappears and not the other!
> I don't understand why the 500/2000 uses a nonstandard pinout; what's the
> motivation? Secondly, since you have to make two sets of ROMs anyway
> (a 16-bit version and a 32-bit version), there's no reason to choose
> an incompatible pinout for the 3000's ROMs (i.e. backward compatability
> is not an issue). Could you please clarify? (thanks!)

I'm not sure what you mean by non-standard.  The ROM pinout used in the A500
and A2000 is the one used by all of the Japanese ROM vendors, who are/were
the only ones offering masked ROM in 16-bit x 128K format.  When the current
crop of EPROM's in the same class came out, the EPROM vendors chose not to
make their pinouts conform to this pre-existing defacto standard.  So, for
pre-production systems we need to support both, although in the long term,
the ROM pinout will prevail.  Perhaps the EPROM vendors will see the light
if they wish to promote socket-level interchangability.

-- 
George Robbins - now working for,     uucp:   {uunet|pyramid|rutgers}!cbmvax!grr
but no way officially representing:   domain: grr@cbmvax.commodore.com
Commodore, Engineering Department     phone:  215-431-9349 (only by moonlite)

daveh@cbmvax.commodore.com (Dave Haynie) (05/29/90)

In article <3276@eklektik.UUCP> danbabcock@eklektik.UUCP (/dev/ph1) writes:

>I hope it's the nonstandard pinout that disappears and not the other!

How do pick which one is standard?  Since we've been using the standard 
pinout, as dictated by Japan, Inc. since before there WERE EPROMS in the
128K x 16 or 256K x 16 package, I claim that the ROM pinout IS the
standard.  Intel can come along any time they please, I suppose, and 
choose a different pinout, but that is not going to make it the standard.
It's unfortunate they didn't see fit to use the already existing pinout
for the EPROMs, but it's something we'll have to live with.  We do
expect the majority of A3000s to have ROMs in them.

   "The great thing about standards is that there are so many of them"

>-- Dan Babcock

-- 
Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests"
   {uunet|pyramid|rutgers}!cbmvax!daveh      PLINK: hazy     BIX: hazy
	"I have been given the freedom to do as I see fit" -REM

p554mve@mpirbn.UUCP (Michael van Elst) (06/02/90)

In article <11907@cbmvax.commodore.com> daveh@cbmvax (Dave Haynie) writes:
>   "The great thing about standards is that there are so many of them"

Standards, they are fun
Let's make another one.

:-)

-- 
Michael van Elst
UUCP:     universe!local-cluster!milky-way!sol!earth!uunet!unido!mpirbn!p554mve
Internet: p554mve@mpirbn.mpifr-bonn.mpg.de
                                "A potential Snark may lurk in every tree."